The present invention relates to a walk behind working machine operated by an operator walking behind the machine and gripping a grip portion of a handle of the machine.
One example of walk behind working machines is known from, for example, Japanese Utility Model Publication No. SHO-58-32578 entitled xe2x80x9cA SELF-PROPELLED LAWNMOWERxe2x80x9d. The known lawnmower is described below with reference to FIG. 23 hereof.
When cutting a lawn 201 with the walk behind lawnmower 200, an operator 204 shifts a clutch lever 207 in a direction as shown by an arrow from a position, shown in a phantom line, while gripping a grip 206 of a handle 205 under a condition where a cutter in a housing 203 is rotated by an engine 202. With such an operation, a running clutch, interposed between the engine 202 and rear wheels 208, is coupled to enable drive power of the engine 202 to be delivered to the rear wheels 208. Rendering the lawnmower 200 to be self-propelled with the rear wheels 208 and front wheels 209 allows the cutter to cut the lawn 201.
Normally, the running clutch used in the lawnmower employs a dog-clutch. The dog-clutch is arranged such that sliding a shifter in a case toward a worm gear causes clutch teeth of the shifter to be brought into mating engagement with worm teeth of the worm gear to assume a coupled state. Such a dog-clutch is instantaneously operated from an uncoupled state to the coupled state. For this reason, when the operator 204 shifts the clutch lever 207 in the direction as shown by the arrow from teh position shown by the phantom line while gripping the grip 206 of the handle 205, the clutch is apt to be instantaneously brought into the coupled state to cause the lawnmower 200 to rapidly start off at an initial speed V1. When this occurs, since the operator 204 holds the grip 206, rapid taking off of the lawnmower 200 causes the operator 204 to be pulled from the lawnmower 200. Therefore, in order to have the walk behind lawnmower 200 to start off smoothly, the operator must start walking in synchronism with the coupling operation of the clutch.
However, if the operator 204 begins to walk at a low speed, a forward movement of the lawnmower 200 is interrupted, causing the rear wheels 208 of the lawnmower 200 to slip or causing the front wheels 209 to lift up as shown by the arrow. As a result, there are some instances where the grass 201 is caused to be laid down or to be torn off and where the cutter tends to be lifted up due to lifting up of the front wheels 209. Thus, it is difficult to cut the grass 201 with a high quality finish using the walk behind lawnmower during the taking off period of the walk behind lawnmower 200.
Because of the reasons described above, in order to allow the walk behind lawnmower 200 to start off in a suitable manner, it is required for the operator to predict the speed at which the lawnmower takes off, thereby requiring skilled handling of the walk behind lawnmower 200 in order to cut the grass 201 with a desired finish. For this reason, an attempt has heretofore been made with a view to providing a walk behind lawnmower, which is enabled to carry out a smooth taking off, into practical use.
It is therefore an object of the present invention to provide a walk behind working machine which has excellent operability during a take-off operation to achieve a desired smooth take-off.
According to a first aspect of the present invention, there is provided a walk behind working machine which comprises: a machine body; a drive source mounted on the machine body; right and left drive wheels carried on a rear portion of the machine body and driven by actuation of the drive source; a running clutch provided between the right and left drive wheels and coupled to the drive source such that it allows use in a slipping phase; operating handles extending rearward from the machine body; and a grip/clutch lever mounted on the handles swingably between a forward position and a rearward position, the grip/clutch lever being connected to the running clutch via a clutch cable such that the running clutch is coupled when the grip/clutch lever is shifted to the forward position, and is uncoupled when the grip/clutch lever is shifted to the rearward position, whereby the working machine is capable of traveling in the clutch slipping phase during the course of shift of the grip/clutch lever between the forward and rearward positions.
By thus bringing the grip/clutch lever into a clutch slipping phase during its forward pushing, the walk behind working machine starts running at a low speed. In this instance, since the operator merely walks forward while applying the forward pushing force onto the grip/clutch lever, it is possible for the operator to handle the walk behind working machine in a natural motion, making it possible to have the walk behind working machine start off smoothly. For this reason, it is possible to cut grass with the walk behind working machine in a high quality finish from the start of work.
In addition, the walk behind working machine may start off at a low speed during the operator""s forward pushing operation of the grip/clutch lever, allowing the operator to follow the start-off movement of the walk behind working machine in a natural motion.
Further, since the grip/clutch lever serves as both a clutch lever and a handle grip as a result of it being rendered capable of handling the machine body by gripping the grip/clutch lever, it is possible to perform a clutch operation with the grip/clutch lever gripped. Accordingly, it is possible to save troublesome steps for removing one hand from the handle grip with the clutch lever handled with the removed hand as required in the conventional working machine, with a resultant decrease in the operator""s load.
In a preferred form, the grip/clutch lever includes stoppers mounted to proximal ends thereof for restricting fore and aft movements of the grip/clutch lever beyond the forward and rearward positions. The stoppers are thus separated from the grip of the grip/clutch lever during a handling operation of the grip/clutch lever, thereby avoiding interference of the operator""s hand with the stoppers.
Desirably, the grip/clutch lever further includes a hold lever mounted to the handles forwardly of the grip/clutch lever so that by gripping the grip/clutch lever and the hold lever together as the grip/clutch lever is tilted or swung toward the hold lever until it comes to the forward position, the grip/clutch lever is retained at the forward position. By thus tilting the grip/clutch lever to the forward position while gripping the grip/clutch lever together with the hold lever, the grip/clutch lever is retained at the forward position. Since the grip/clutch lever is retained at the forward position by merely gripping the grip/clutch lever together with the hold lever, it is possible for the grip/clutch lever to be retained at the forward position in a further simplified manner.
The hold lever is swingable between a forward stationary position and a rearward gripping position so that when the hold lever is gripped together with the grip/clutch lever at the forward position, the hold lever is retained at the gripping position and when the hold lever is released from the gripped state, it is returned to the stationary position. Thus, since the hold lever is arranged to have the capability of tilting between the forward stationary position and the rearward gripping position, gripping the hold lever and the grip/clutch lever together causes the hold lever to be retained at the gripping position for thereby allowing the grip/clutch lever to be retained at the forward position. On the other hand, there is an instance where it is desired for the hold lever to be kept at the forward position by continuously pushing the grip/clutch lever forward without gripping the hold lever. In such a case, since the hold lever is rendered capable of returning to the stationary position, it is possible for the operator""s hand to be precluded from interfering with the hold lever during continuous forward pushing movement of the grip/clutch lever. Thus, the presence of the capability for tilting the hold lever enables the operation for retaining the grip/clutch lever at the forward position to be carried out in the two different modes. As a result, a suitable operating method can be selected from the two different modes in accordance with the working status of the walk behind working machine, with the result that the maneuverability or operability of the walk behind working machine is further improved.
With the stopper mounted to the proximal end of the hold lever for restricting the fore and aft movements of the hold lever at the stationary position and the gripping position, it becomes possible to separate the stopper from the grip of the hold lever to thereby prevent the operator""s hand from interfering with the stopper during the handling operation of the hold lever.
According to a second aspect of the present invention, there is provided a walk behind working machine which comprises: a machine body; a drive source mounted on the machine body; right and left drive wheels carried on a rear portion of the machine body and driven by actuation of the drive source; a running clutch provided between the right and left drive wheels and coupled to the drive source such that it allows use in a slipping phase; operating handles extending rearward from the machine body; a grip/clutch lever mounted on the handles swingably between a forward position and a rearward position, the grip/clutch lever being connected to the running clutch via a clutch cable such that the running clutch is coupled when the grip/clutch lever is shifted to the forward position, and is uncoupled when the grip/clutch lever is shifted to the rearward position; and a hold lever mounted on the handles forwardly of the grip/clutch lever, the grip/clutch lever and the hold lever being spaced a predetermined distance from each other when the grip/clutch lever, after it is swung toward the hold lever until it comes to the forward position, is gripped together with the hold lever.
Thus, by swinging the grip/clutch lever to the forward position, the running clutch is brought into the slipping phase, thereby enabling the walk behind working machine to start off at a low speed. That is, the operator may advance forward while applying a pushing force to the grip/clutch lever. This allows the operator to handle the walk behind working machine in a natural motion, thereby enabling the walk behind working machine to start off in a smooth manner.
In addition, merely tilting the grip/clutch lever to the forward position compels the walk behind working machine to start off at a low speed. As a result, the operator is allowed to follow the start off operation of the walk behind working machine in a natural motion.
Further, by gripping the grip/clutch lever to allow the machine body to be handled, the grip/clutch lever may commonly serve as the clutch lever and the handle grip, permitting the clutch operation to be performed with the grip/clutch lever retained in the gripped state. Consequently, it is possible to save troublesome steps, which would be required in the conventional working machine, for removing one hand from the handle grip and for handling the clutch lever with the removed hand.
When the walk behind working machine ascends a sloped hill in an exemplary case, large drive power is required. When the walk behind working machine travels in a non-working state, it is desired that the working machine advances at a high speed. To this end, as described above, when the grip/clutch lever, remaining at the forward position, is gripped with the hold lever, the grip/clutch lever is so constructed as to be separated from the hold lever by a given distance. For this reason, strongly gripping the grip/clutch lever and the hold lever enables the grip/clutch lever to be strongly urged toward the hold lever. With such an action, a strong urging force can be applied to the running clutch, thereby enabling the slipping phase to be adjusted into a less slipping state. Therefore, the drive power of the walk behind working machine is increased depending on the working status while allowing the working machine to travel at a higher speed.